Monday, January 12, 2015

Hyena hygiene is pretty similar to what you would expect
from any large carnivore. Hyenas get clean by licking themselves (or even
better, by getting others to lick them), although, like domestic dogs, they
jump all over the opportunity to roll in something gross they find on the
ground.So, while being clean isn’t
always the highest priority for hyenas, it is not uncommon for us to find them
cleaning themselves or others.

Despite its function, grooming behavior doesn’t always
appear as hygienic to us humans as it does to the hyenas. Like seeing your pet
dog thoroughly licking its anogenital region, observing hyenas during bath
time is not always the most pleasant experience. CAMI, for example, decided to
ruin our peaceful evening the other night be loudly grooming her phallus right
outside of my car window. I have heard Kenna complain on multiple occasions
that a cleanliness-obsessed cub cleaning its phallus ruined her attempts to
record vocalizations from a neighboring adult.

CAMI gave came right up to the car to make sure we could clearly see and hear her dedication to cleanliness.

Despite their unsightliness, these behaviors are familiar to
anyone who spends a considerable amount of time observing animals, and we don’t
really bat an eye when we see them. We were, however, treated to a new variety
of unusual grooming behavior the other night by EREM and ARBA, twins who
currently each have pairs of cubs about the same age at the current Happy Zebra clan communal
den. These two moms often arrive at the same time, and like good mothers, get
right down to nursing and grooming their kids.

ARBA (left) and EREM (right), each dutifullynursing and grooming one of their two cubs. Wait, what exactly is EREM grooming?

While watching EREM and ARBA grooming their kids, we noticed
them both take particular care to groom the anogenital region of their cubs.
This didn’t seem particularly unusual to us, until we noticed that the cub
would often distend its anal sac during this process. The cub’s mom would then
thoroughly groom the anal sac, the area where the cub will eventually begin
producing the scent marking substance called paste. Not only did we notice both
EREM and ARBA doing this, but their cubs each took a turn so that both
littermates got a thorough anal sac grooming from their moms.

Smaug distending his anal sac so EREM can give it a thorough cleaning, while Puff anxiously awaits his turn.

What is going on here? I don’t know, but I wonder whether
this grooming behavior is purely hygienic or if grooming of the anal sac is an
important part of the ontogeny of paste production. Paste is produced by
microbiota that inhabit the hyena’s anal sac, so proper maintenance of the sac
could be important to encourage the colonization of the bacteria that will
eventually produce the individual’s scent. Alternatively, a cub’s mom may be directly inoculating her offspring’s anal sac with these bacteria from her mouth. While these explanations are purely speculative, there are others who know much more about paste production than I. If you
are interested in learning about how hyenas host specific bacteria in their
anal sac that produce their scent, check out research by Dr. Kevin R. Theis (https://kevinrtheis.wordpress.com/),
who has discovered some very cool stuff about the complex symbiosis that underlies
hyena olfactory communication.

Help Support the Research

You can help support our research by making a donation to the Hyena Research Fund at MSU. Your contributions provide necessary resources for the students and scientists to continue our work. Use the link below to make a donation or contact MSU for additional details.